Trigger mechanisms for surgical instruments and surgical instruments including the same

ABSTRACT

A trigger assembly of a surgical instrument includes a trigger, a first linkage, a second linkage, and a slider block configured such that moving the manipulation portion in a first direction relative to a housing of the surgical instrument translates the slider block along a longitudinal axis relative to the housing. Another trigger assembly of a surgical instrument includes a trigger and a coupling sphere rotatably captured within a cavity of a retention portion of the trigger such that movement of a manipulation portion of the trigger relative to the housing translates the coupling sphere along the longitudinal axis relative to the housing.

FIELD

The present disclosure relates to surgical instruments and, moreparticularly, to trigger mechanisms for surgical instruments andsurgical instruments including the same.

BACKGROUND

A surgical forceps is a pliers-like surgical instrument that relies onmechanical action between its jaw members to grasp, clamp, and constricttissue. Electrosurgical forceps utilize both mechanical clamping actionand energy to heat tissue to treat, e.g., coagulate, cauterize, or seal,tissue. Typically, once tissue is treated, the surgeon has to accuratelysever the treated tissue. Accordingly, many electrosurgical forceps aredesigned to incorporate a knife or cutting member utilized toeffectively sever the treated tissue.

SUMMARY

As used herein, the term “distal” refers to the portion that is beingdescribed which is further from a user, while the term “proximal” refersto the portion that is being described which is closer to a user.Further, to the extent consistent, any or all of the aspects detailedherein may be used in conjunction with any or all of the other aspectsdetailed herein.

Provided in accordance with aspects of the present disclosure is atrigger assembly of a surgical instrument that includes a trigger, afirst linkage, a second linkage, e.g., a T-linkage, and a slider block.The trigger includes a manipulation portion, a linkage portion, and apivot portion disposed between the manipulation and linkage portions.The pivot portion is configured for pivotable engagement with a housingof a surgical instrument such that moving the manipulation portion in afirst direction relative to the housing pivots the pivot portionrelative to the housing to thereby move the linkage portion in a second,opposite direction relative to the housing. The first linkage defines afirst floating end portion and a second pivoting end portion. The secondpivoting end portion is configured for pivotable engagement with thehousing. The second linkage includes a crossbar and an upright. Thecrossbar is pivotably coupled to and extends between the linkage portionof the trigger and the first floating end portion of the first linkage.The slider block is operably engaged with the upright of the secondlinkage such that movement of the upright in response to movement of themanipulation portion of the trigger relative to the housing translatesthe slider block along a longitudinal axis relative to the housing.

In an aspect of the present disclosure, the manipulation portion of thetrigger is disposed on one side of the longitudinal axis and the linkageportion of the trigger is pivotably coupled to the crossbar of thesecond linkage on a second, opposite side of the longitudinal axis.Additionally or alternatively, the linkage portion of the triggertraverses the longitudinal axis.

In another aspect of the present disclosure, the second pivoting endportion of the first linkage is disposed on one side of the longitudinalaxis and the first floating end portion of the trigger is pivotablycoupled to the crossbar of the second linkage on a second, opposite sideof the longitudinal axis. Additionally or alternatively, the firstlinkage includes a body extending between the first floating end portionand the second pivoting end portion and traversing the longitudinalaxis.

In another aspect of the present disclosure, the slider block isoperably engaged with the upright of the second linkage via apost-opening, e.g., post-slot, post-aperture, etc. engagement such that,in response to longitudinal and vertical motion of the upright of thesecond linkage, the slider block is only moved longitudinally.

In still another aspect of the present disclosure, the first linkage isarcuate and defines a distally-facing concave side and aproximally-facing convex side. In such aspects, the concave side of thefirst linkage may define a volume wherein the slider block is disposedin the volume in at least one position of the manipulation portion ofthe trigger relative to the housing.

In yet another aspect of the present disclosure, at least a portion ofat least one of: the trigger, the second linkage, or the first linkagedefines a bifurcated configuration for receipt of a drive bartherebetween.

In still yet another aspect of the present disclosure, at least one of:the trigger, the second linkage, or the first linkage is formed as asingle, monolithic piece of material.

Another trigger assembly of a surgical instrument provided in accordancewith the present disclosure includes a trigger and a coupling sphere.The trigger includes a manipulation portion, a retention portion, and apivot portion disposed between the manipulation and retention portions.The pivot portion is configured for pivotable engagement with a housingof a surgical instrument such that moving the manipulation portion in afirst direction relative to the housing pivots the pivot portionrelative to the housing to thereby move the retention portion in asecond, opposite direction relative to the housing. The retentionportion defines a cavity. The coupling sphere is rotatably capturedwithin the cavity of the retention portion. At least a portion of thecavity defines an internal surface complementary to an external surfaceof the coupling sphere such that movement of the manipulation portion ofthe trigger relative to the housing translates the coupling sphere alonga longitudinal axis relative to the housing.

In an aspect of the present disclosure, the manipulation portion of thetrigger is disposed on one side of the longitudinal axis and theretention portion of the trigger extends to a second, opposite side ofthe longitudinal axis.

In another aspect of the present disclosure, the trigger is formed as asingle, monolithic piece of material.

In still another aspect of the present disclosure, the coupling sphereis formed from first and second components engaged with one another viasnap-fitting.

In yet another aspect of the present disclosure, the coupling sphere isconfigured for positioning about a drive bar.

In still yet another aspect of the present disclosure, the couplingsphere includes an internal post extending therethrough.

In another aspect of the present disclosure, the retention portion ofthe trigger includes first and second spaced-apart side walls configuredfor positioning on opposing sides of the coupling sphere. In suchaspects, the first and second spaced-apart side walls may includeproximal and distal ends extending inwardly to retain the couplingsphere longitudinally therebetween.

In another aspect of the present disclosure, the retention portion ofthe trigger includes proximal and distal fork ends configured forpositioning at proximal and distal ends, respectively, of the couplingsphere. In such aspects, the distal fork end may include a connectorconnecting first and second fork legs thereof.

BRIEF DESCRIPTION OF DRAWINGS

The above and other aspects and features of the present disclosure willbecome more apparent in view of the following detailed description whentaken in conjunction with the accompanying drawings wherein likereference numerals identify similar or identical elements.

FIG. 1 is a perspective view of an electrosurgical forceps provided inaccordance with the present disclosure;

FIG. 2A is an enlarged, perspective view of an end effector assembly ofthe electrosurgical forceps of FIG. 1 wherein first and second jawmembers of the end effector assembly are disposed in a spaced-apartposition;

FIG. 2B is an enlarged, perspective view of the end effector assembly ofFIG. 2A wherein the first and second jaw members are disposed in anapproximated position;

FIG. 3A is a side view of a proximal portion of the electrosurgicalforceps of FIG. 1 with a movable handle and trigger thereof disposed inrespective un-actuated positions;

FIG. 3B is a side view of the proximal portion of the electrosurgicalforceps shown in FIG. 3A with the movable handle disposed in an actuatedposition and the trigger disposed in the un-actuated position;

FIG. 3C is a side view of the proximal portion of the electrosurgicalforceps shown in FIG. 3A with the movable handle and trigger disposed inrespective actuated positions;

FIG. 4A is a side view of another proximal portion of theelectrosurgical forceps of FIG. 1 with portions removed to illustrate atrigger assembly thereof with the trigger disposed in the un-actuatedposition;

FIG. 4B is a side view of the proximal portion of the electrosurgicalforceps shown in FIG. 4A with portions removed to illustrate the triggerassembly with the trigger disposed in the actuated position;

FIG. 5A is a side view of still another proximal portion of theelectrosurgical forceps of FIG. 1 with portions removed to illustrateanother trigger assembly thereof with the trigger disposed in theun-actuated position;

FIG. 5B is a side view of the proximal portion of the electrosurgicalforceps shown in FIG. 5A with portions removed to illustrate the triggerassembly with the trigger disposed in the actuated position;

FIG. 5C is an enlarged, side, partial cross-sectional view of theproximal portion of the electrosurgical forceps shown in FIG. 5A withportions removed to illustrate the trigger assembly with the triggerdisposed in the actuated position;

FIG. 6A is a perspective view the coupling sphere of the triggerassembly of FIG. 5A;

FIGS. 6B-6D are side, front, and top views, respectively, of onecomponent of the coupling sphere of FIG. 6A;

FIGS. 7A-7C are side, cross-sectional, and front views, respectively, ofthe trigger of the trigger assembly of FIG. 5A; and

FIGS. 8A and 8B are side and perspective views, respectively, of anothertrigger configured for user with the trigger assembly of FIG. 5A.

DETAILED DESCRIPTION

Referring to FIG. 1, a surgical instrument provided in accordance withthe present disclosure is shown configured as a bipolar electrosurgicalforceps 10 for use in connection with endoscopic surgical procedures,although the present disclosure is equally applicable for use with othersurgical instruments such as those for use in endoscopic and/ortraditional open surgical procedures. Forceps 10 generally includes ahousing 20, a handle assembly 30, a rotating assembly 60, a triggerassembly 80, an activation assembly 90, and an end effector assembly 100including first and second jaw members 110, 120.

Forceps 10 further includes a shaft 12 having a distal end portion 14configured to engage (directly or indirectly) end effector assembly 100and a proximal end portion 16 that engages (directly or indirectly)housing 20. Rotating assembly 60 is rotatable in either direction torotate shaft 12 and end effector assembly 100 relative to housing 20 ineither direction. Housing 20 houses the internal working components offorceps 10.

An electrosurgical cable 300 connects forceps 10 to an electrosurgicalgenerator “G” or other suitable energy source, although forceps 10 mayalternatively be configured as a handheld instrument incorporatingenergy-generating and/or power components thereon or therein. Cable 300includes wires (not shown) extending therethrough, into housing 20, andthrough shaft 12, to ultimately connect electrosurgical generator “G” tojaw member 110 and/or jaw member 120 of end effector assembly 100.Activation button 92 of activation assembly 90 is disposed on housing 20are electrically coupled between end effector assembly 100 and cable 300to enable the selective supply of energy to jaw member 110 and/or jawmember 120, e.g., upon activation of activation button 92. However,other suitable electrical connections and/or configurations forsupplying electrosurgical energy to jaw member 110 and/or jaw member 120may alternatively be provided, as may other suitable forms of energy,e.g., ultrasonic energy, microwave energy, light energy, thermal energy,etc.

Forceps 10 additionally includes a knife assembly 170 (FIG. 2A) operablycoupled to trigger assembly 80 and extending through housing 20 andshaft 12. One or both of jaw members 110, 120 defines a knife channel125 (FIG. 2A) configured to permit reciprocation of a knife blade 172(FIG. 2A) of knife assembly 170 (FIG. 2A) therethrough, e.g., inresponse to actuation of trigger 82 of trigger assembly 80. Triggerassembly 80 is described in greater detail below as are otherembodiments of trigger assemblies configured for use with forceps 10.

With additional reference to FIGS. 2A and 2B, end effector assembly 100,as noted above, is disposed at distal end portion 14 of shaft 12 andincludes a pair of jaw members 110 and 120 pivotable between aspaced-apart position and an approximated position for grasping tissuetherebetween. End effector assembly 100 is designed as a unilateralassembly, e.g., wherein one of the jaw members 120 is fixed relative toshaft 12 and the other jaw member 110 is movable relative to both shaft12 and the fixed jaw member 120. However, end effector assembly 100 mayalternatively be configured as a bilateral assembly, e.g., wherein bothjaw member 110 and jaw member 120 are movable relative to one anotherand with respect to shaft 12.

Each jaw member 110, 120 of end effector assembly 100 includes anelectrically-conductive tissue-contacting surface 116, 126.Tissue-contacting surfaces 116 are positioned to oppose one another forgrasping and treating tissue. More specifically, tissue-contactingsurfaces 116, 126 are electrically coupled to the generator “G,” e.g.,via cable 300, and activation button 92 to enable the selective supplyof energy thereto for conduction through tissue grasped therebetween,e.g., upon activation of activation button 92. One or both oftissue-contacting surfaces 116, 126 may include one or more stop members(not shown) extending therefrom to define a minimum gap distance betweenelectrically-conductive tissue-contacting surfaces 116, 126 in theapproximated position of jaw members 110, 120, facilitate grasping oftissue, and/or inhibit shorting between electrically-conductivetissue-contacting surfaces 116, 126. The stop member(s) may be formed atleast partially from an electrically-insulative material or may beeffectively insulative by electrically isolating the stop member(s) fromone or both of the electrically-conductive tissue-contacting surfaces116, 126.

A pivot pin 103 of end effector assembly 100 extends transverselythrough aligned apertures defined within jaw members 110, 120 and shaft12 to pivotably couple jaw member 110 to jaw member 120 and shaft 12. Acam pin 105 of end effector assembly 100 extends transversely throughcam slots defined within jaw members 110, 120 and is operably engagedwith a distal end portion of a drive bar 152 (FIGS. 4A and 4B) of adrive assembly (only drive bar 152 (FIGS. 4A and 4B) of the driveassembly is shown) such that longitudinal translation of drive bar 152(FIGS. 4A and 4B) through shaft 12 translates cam pin 105 relative tojaw members 110, 120. More specifically, distal translation of cam pin105 relative to jaw members 110, 120 urges cam pin 105 distally throughthe cam slots to thereby pivot jaw members 110, 120 from thespaced-apart position towards the approximated position, although camslots may alternatively be configured such that proximal translation ofcam pin 105 pivots jaw members 110, 120 from the spaced-apart positiontowards the approximated position. One suitable drive assembly isdescribed in greater detail, for example, in U.S. Pat. No. 9,655,673,the entire contents of which are hereby incorporated herein byreference.

Referring to FIGS. 1-3C, handle assembly 30 includes a fixed handle 50and an actuator, e.g., movable handle 40. Fixed handle 50 is integrallyassociated with housing 20 and movable handle 40 is movable relative tofixed handle 50. Movable handle 40 is ultimately connected to the driveassembly (not shown) that, together, mechanically cooperate to impartmovement of jaw members 110 and 120 between the spaced-apart andapproximated positions to grasp tissue between electrically-conductivesurfaces 116, 126, respectively. More specifically, pivoting of movablehandle 40 relative to fixed handle 50 from an un-actuated positiontowards an actuated position pivots jaw members 110, 120 from thespaced-apart position towards the approximated position. On the otherhand, when movable handle 40 is released or returned towards the initialposition relative to fixed handle 50, jaw members 110, 120 are returnedtowards the spaced-apart position. A biasing spring (not shown)associated with movable handle 40 and/or the drive assembly may beprovided to bias jaw members 110, 120 towards a desired position, e.g.,the spaced-apart position or the approximated position.

Fixed handle 50 operably supports activation button 92 of activationassembly 90 thereon in an in-line position, wherein activation button 92is disposed in the actuation path of movable handle 40. In this manner,upon pivoting of movable handle 40 relative to fixed handle 50 from theactuated position to an activated position, protrusion 94 of movablehandle 40 is urged into contact with activation button 92 to therebyactivate activation button 92 and initiate the supply of energy toelectrically-conductive surfaces 116, 126, e.g., to treat tissue graspedtherebetween. Alternatively, actuation button 92 may be disposed in anyother suitable position, on housing 20 or remote therefrom, tofacilitate manual activation by a user to initiate the supply of energyto electrically-conductive surfaces 116, 126.

With reference to FIGS. 1-2B and 4A-4B, as noted above, trigger assembly80 is operably coupled to knife blade 172 of knife assembly 170. Morespecifically, trigger 82 of trigger assembly 80 is selectivelyactuatable, e.g., from an un-actuated positon (FIGS. 3A and 4A) to anactuated position (FIGS. 3C and 4B), to deploy knife blade 172 distallythrough jaw members 110, 120 to cut tissue grasped betweenelectrically-conductive surfaces 116, 126. Knife assembly 170 includesknife blade 172 and a knife bar 174 engaged with and extendingproximally from knife blade 172 through shaft 12 and drive bar 152 intohousing 20 where knife bar 174 is operably coupled with trigger assembly80, as detailed below.

Referring to FIGS. 4A and 4B, trigger assembly 80 includes trigger 82, alink 84, e.g., a T-link 84, a link 86, e.g., an arcuate linkage 86although other configurations, e.g., linear, angled, etc. are alsocontemplated, and a slider block 88. In this manner, trigger assembly 80defines a four-bar mechanical linkage assembly for driving slider block88. An upright 85 e of T-link 84, a body 87 c of arcuate link 86, and alinkage portion 83 b of trigger 82 define bifurcated configurationsincluding first and second spaced-apart segments disposed on either sideof drive bar 152. The first and second segments are mirror-images of oneanother and, thus, upright 85 e of T-link 84, body 87 c of arcuate link86, and linkage portion 83 b of trigger 82 are detailed below in thesingular for simplicity purposes. As an alternative to bifurcatedconfigurations, one or more of upright 85 e of T-link 84, body 87 c ofarcuate link 86, and linkage portion 83 b of trigger 82 may include onlyone segment, e.g., disposed on one side of drive bar 152.

Trigger 82 includes a manipulation portion 83 a extending from housing20 to enable manual manipulation thereof by a user. Trigger 82 furtherincludes a linkage portion 83 b and a pivot portion 83 c. Trigger 82 ismonolithically formed from a single piece of material or is otherwiseformed, e.g., via fixed engagements, such that manipulation portion 83a, linkage portion 83 b, and pivot portion 83 c are fixed relative toone another. Pivot portion 83 c is pivotably coupled within housing 20via receipt of a pair of pivot posts 83 d extending outwardly fromopposite sides of pivot portion 83 c within corresponding apertures (notshown) defined on opposed interior sides of housing 20. Pivot portion 83c is pivotably coupled to housing 20 at a position below a longitudinalaxis “X-X” defined by shaft 12, drive bar 152, and/or knife bar 172.Further, pivot portion 83 c is disposed between manipulation portion 83a, which extends from housing 20, and linkage portion 83 b, which isdisposed within housing 20, such that movement of manipulation portion83 a in one direction, e.g., proximally, urges linkage portion 83 b inthe opposite direction, e.g., distally. However, other configurationsare also contemplated, e.g., wherein pivot portion 83 c is offsetrelative to manipulation portion 83 a and/or linkage portion 83 b.

Linkage portion 83 b of trigger 82 extends from pivot portion 83 c belowlongitudinal axis “X-X” to a free end portion thereof above longitudinalaxis “X-X” and is pivotably coupled at the free end portion thereof to aproximal end portion 85 b of a crossbar 85 a of T-link 84. T-link 84includes crossbar 85 a defining proximal and distal end portions 85 b,85 c, respectively, and an upright 85 e extending from an intermediateportion 85 d of crossbar 85 a between proximal and distal end portions85 b, 85 c, respectively, e.g., in generally perpendicular orientationor other suitable orientation relative to crossbar 85 a. Upright 85 e ofT-link 84 is fixed relative to, e.g., monolithically formed withintermediate portion 85 d of crossbar 85 a at a position abovelongitudinal axis “X-X” and extends downwardly therefrom to a free endportion 85 f defining a slot 85 g. Slot 85 g extends to or traverseslongitudinal axis “X-X” and is configured to receive anoutwardly-extending pivot post 89 b extending outwardly from body 89 aof slider block 88.

Arcuate link 86 includes an upper end portion 87 a, a lower end portion87 b, and a body 87 c extending between upper and lower end portions 87a, 87 b, respectively. Upper end portion 87 a of arcuate link 86 isdisposed above longitudinal axis “X-X” and is pivotably coupled todistal end portion 85 c of crossbar 85 a of T-link 84 above longitudinalaxis “X-X.” Body 87 c of arcuate link 86 traverses longitudinal axis“X-X” from extending from upper end portion 87 a of arcuate link 86 isto lower end portion 87 b of arcuate link 86. Lower end portion 87 b ofarcuate link 86 is disposed below longitudinal axis “X-X” and ispivotably coupled to housing 20, e.g., via a pivot pin, belowlongitudinal axis “X-X”. Body 87 c of arcuate link 86, in embodiments,defines an arcuate configuration wherein the concave side thereof isproximally-facing and the convex side thereof is distally-facing. Thisconfiguration provides suitable clearance to enable receipt of sliderblock 88 within the concave volume defined by body 87 c on the concaveside thereof Alternatively, as noted above, link 86 need not be arcuatebut may define a linear, angled, or other suitable configuration.

Slider block 88, as noted above, includes a body 89 a and anoutwardly-extending pivot post 89 b extending outwardly from body 89 a.Body 89 a of slider block 88 is slidably disposed about drive bar 152and includes an internal post, posts, or other suitable engagementstructure(s) (not shown) extending through a longitudinal slot 153defined within drive bar 152 and into engagement with knife bar 174 tofix body 89 a of slider block 88 relative to knife bar 174. Slider block88 is slidable about drive bar 152 and along longitudinal axis “X-X” tothereby translate knife bar 174 to, in turn, deploy knife blade 172distally through jaw members 110, 120 to cut tissue grasped betweenelectrically-conductive surfaces 116, 126 and to retract knife blade 172subsequent to tissue cutting (see FIG. 2A).

Continuing with reference to FIGS. 4A and 4B, as a result of theabove-detailed configuration, moving manipulation portion 83 a oftrigger 82 proximally relative to housing 20, e.g., from the un-actuatedposition (FIG. 4A) towards the actuated position (FIG. 4B), rotatespivot portion 83 c counterclockwise (from the orientation illustrated inFIGS. 4A and 4B) relative to housing 20 to thereby move linkage portion83 b distally. This distal movement of linkage portion 83 b urges T-link84 distally. More specifically, the distal movement of linkage portion83 b urges crossbar 85 a distally to thereby urge upper end portion 87 aof arcuate linkage 86 distally such that lower end portion 87 b ofarcuate linkage 86 is rotated counterclockwise (from the orientationillustrated in FIGS. 4A and 4B) relative to housing 20 about the pivotcoupling lower end portion 87 b with housing 20. Further, the distalmovement of linkage portion 83 b urges crossbar 85 a distally to therebypull upright 85 e distally along with crossbar 85 a. As upright 85 e ispulled distally, pivot post 89 b, which is received within slot 85 g ofupright 85 e, is likewise pulled distally such that body 89 a of sliderblock 88 is pulled distally about drive bar 152 and relative to housing20 and shaft 12. This distal translation of slider block 88 translatesknife bar 174 distally through shaft 12 and relative to end effectorassembly 100 to deploy knife blade 172 distally through jaw members 110,120 to cut tissue grasped between electrically-conductive surfaces 116,126 (see FIG. 2A).

It is noted that slot 85 g enables upright 85 e to include a relativelyminor vertical range of motion in response to pivoting of trigger 82 andarcuate linkage 86, without imparting vertical motion to slider block88. In embodiments, slot 85 g may be cam-shaped to vary the mechanicaladvantage during travel. Further, the above-detailed configurationprovides a four-bar mechanical linkage facilitating deployment of knifeblade 172 (FIG. 2A) in response to pivoting of trigger 82. Inembodiments, a return spring (not shown) may be provided to returnmanipulation portion 83 a of trigger 82 towards the un-actuated positionand, thus, to return knife blade 172 to the retracted position (FIG.2A). Upon release of manipulation portion 83 a of trigger 82 (inembodiments where a return spring is provided) or return of manipulationportion 83 a of trigger 82 towards the un-actuated position, trigger 82is pivoted clockwise (from the orientation illustrated in FIGS. 4A and4B) relative to housing 20 to rotate pivot portion 83 c clockwise (fromthe orientation illustrated in FIGS. 4A and 4B) relative to housing 20to thereby move linkage portion 83 b proximally. This proximal movementof linkage portion 83 b pulls T-link 84 proximally, pulling crossbar 85a proximally to thereby pull upper end portion 87 a of arcuate linkage86 proximally such that lower end portion 87 b of arcuate linkage 86 isrotated clockwise (from the orientation illustrated in FIGS. 4A and 4B)relative to housing 20 about the pivot coupling lower end portion 87 bwith housing 20. As a result of the above, upright 85 e is movedproximally such that pivot post 89 b, which is received within slot 85 gof upright 85 e, is likewise moved proximally to translate slider block88 proximally about drive bar 152 and relative to housing 20 and shaft12, thereby retracting knife blade 172 proximally from jaw members 110,120 (see FIG. 2A).

Turning to FIGS. 5A-7C, another embodiment of a trigger mechanism 180configured for use with forceps 10 (FIG. 1) is shown. Trigger mechanism180 includes a trigger 182 and a coupling sphere 188.

Referring in particular to FIGS. 5A-5C and 7A-7C, trigger 182 includes amanipulation portion 183 a extending from housing 20 to enable manualmanipulation thereof by a user. Trigger 182 further includes a retentionportion 183 b and a pivot portion 183 c. Trigger 182 is monolithicallyformed from a single piece of material or is otherwise formed, e.g., viafixed engagements, such that manipulation portion 183 a, retentionportion 183 b, and pivot portion 183 c are fixed relative to oneanother. Pivot portion 183 c is pivotably coupled within housing 20 viareceipt of a pair of pivot posts 183 d extending outwardly from oppositesides of pivot portion 183 c within corresponding apertures (not shown)defined on opposed interior sides of housing 20. Alternatively, thisconfiguration may be reversed, e.g., wherein apertures are definedwithin pivot portion 183 c and posts extend inwardly from housing 20, ora pivot pin can be used to couple pivot portion 183 c and housing 20with one another. Pivot portion 183 c is pivotably coupled to housing 20at a position below a longitudinal axis “X-X” defined by shaft 12, drivebar 152, and/or knife bar 172. Further, pivot portion 183 c may bedisposed between manipulation portion 183 a, which extends from housing20, and retention portion 183 b, which is disposed within housing 20,such that movement of manipulation portion 183 a in one direction, e.g.,proximally, urges retention portion 183 b in the opposite direction,e.g., distally. Other configurations are also contemplated.

Retention portion 183 b of trigger 182 extends from pivot portion 183 cbelow longitudinal axis “X-X” to meet or traverse longitudinal axis“X-X,” although other configurations are also contemplated. Retentionportion 183 b defines a base 184 a and a pair of spaced-apart side walls184 b extending from base 184 on either side of drive bar 152. Base 184a and side walls 184 b cooperate to partially enclose a cavity 185 thatis aligned on longitudinal axis “X-X.” Side walls 184 b may defineproximal and distal ends 186 (FIG. 7C) that extend radially inwardly,e.g., defining a curvature, so as to partially bound cavity 185 at theproximal and distal ends thereof. Further, cavity 185 is at leastpartially defined by arcuate interior surfaces of base 184 a and/or sidewalls 184 b such that cavity 185 is at least partially complementary tocoupling sphere 188, which is rotatably captured within cavity 185 (seeFIG. 5C), about a proximal portion of coupling sphere 188 to therebyprovided smooth and consistent urging against coupling sphere 188 totranslate coupling sphere 188 distally as retention portion 183 b ismoved distally and rotated about pivot portion 183 c.

With reference to FIGS. 6A-6D, in conjunction with FIG. 5C, couplingsphere 188, as noted above, is rotatably captured within cavity 185 ofretention portion 183 of trigger 182 (see FIG. 5C). Coupling sphere 188is slidably disposed about drive bar 152 (e.g., defines a lumenextending longitudinally therethrough for receipt of drive bar 152) andis formed from first and second components 189 a, 189 b, e.g.,hemispheres, engaged to one another, e.g., via snap-fit engagement oflegs 189 c within slots 189 d. One of the first or second components 189a, 189 b includes an internal post 189 e or other suitable engagementstructure(s) extending through longitudinal slot 153 defined withindrive bar 152 and into engagement with knife bar 174 to fix couplingsphere 188 relative to knife bar 174. Coupling sphere 188 is slidableabout drive bar 152 and along longitudinal axis “X-X” to therebytranslate knife bar 174 to, in turn, deploy knife blade 172 distallythrough jaw members 110, 120 to cut tissue grasped betweenelectrically-conductive surfaces 116, 126 and to retract knife blade 172subsequent to tissue cutting (see FIG. 2A).

Returning to FIGS. 5A-7C, as a result of the above-detailedconfiguration, moving manipulation portion 183 a of trigger 182proximally relative to housing 20, e.g., from the un-actuated position(FIG. 5A) towards the actuated position (FIG. 5B), rotates pivot portion183 c counterclockwise (from the orientation illustrated in FIGS. 5A and5B) relative to housing 20 to thereby move retention portion 183 bdistally. This distal movement of retention portion 183 b, havingcoupling sphere 188 rotatably captured therein, urges coupling sphere188 distally along longitudinal axis “X-X” (while allowing for rotationof retention portion 183 b without imparting the same to couplingsphere). This distal translation of coupling sphere 188 translates knifebar 174 distally through shaft 12 and relative to end effector assembly100 to deploy knife blade 172 distally through jaw members 110, 120 tocut tissue grasped between electrically-conductive surfaces 116, 126(see FIG. 2A).

In embodiments, a return spring (not shown) may be provided to returnmanipulation portion 183 a of trigger 182 towards the un-actuatedposition and, thus, to return knife blade 172 to the retracted position(FIG. 2A). Upon release of manipulation portion 183 a of trigger 182 (inembodiments where a return spring is provided) or return of manipulationportion 183 a of trigger 182 towards the un-actuated position, trigger182 is pivoted clockwise (from the orientation illustrated in FIGS. 5Aand 5B) relative to housing 20 to rotate pivot portion 183 c clockwise(from the orientation illustrated in FIGS. 5A and 5B) relative tohousing 20 to thereby move retention portion 183 b proximally. Thisproximal movement of retention portion 183 b pulls coupling sphere 188proximally along longitudinal axis “X-X” about drive bar 152 andrelative to housing 20 and shaft 12, thereby retracting knife blade 172proximally from jaw members 110, 120 (see FIG. 2A).

Turning to FIGS. 8A and 8B, another embodiment of a trigger 282configured for use with trigger mechanism 180 (FIGS. 5A-5C) is shown.Trigger 282 is similar to trigger 182 (FIGS. 7A-7C) and, thus, onlydifferences therebetween are described in detail below whilesimilarities are summarily described or omitted entirely.

Trigger 282 includes a manipulation portion 283 a, a retention portion283 b, and a pivot portion 283 c. Retention portion 283 b of trigger 282defines a base 284 a and pair of spaced-apart end forks 284 b. Each endfork 284 b includes first and second spaced-apart fork legs 284 cconfigured for positioning on either side of drive bar 152 (see FIGS.5A-5C). The spaced-apart fork legs 284 c of the distal end fork 284 bmay be connected at free ends thereof via a connector 284 d to increasestructural support and rigidity, as it is the distal end fork 284 b thatis urged into contact with coupling sphere 188 (FIG. 5C) to deploy theknife blade 172 (FIG. 2A).

Base 284 a and end forks 284 b cooperate to define a cavity 285configured to capture coupling sphere 188 (FIG. 5C) therein. Cavity 285is at least partially defined by arcuate interior surfaces of base 284 aand/or end forms 284 b such that cavity 285 is at least partiallycomplementary to coupling sphere 188 (FIG. 5C) about a proximal portionof coupling sphere 188 (FIG. 5C) to thereby provided smooth andconsistent urging against a proximal portion of coupling sphere 188(FIG. 5C) to translate coupling sphere 188 (FIG. 5C) distally asretention portion 283 b is moved distally and rotated about pivotportion 283 c.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of particular embodiments. Those skilled in the artwill envision other modifications within the scope and spirit of theclaims appended hereto.

What is claimed is:
 1. A trigger assembly of a surgical instrument, thetrigger assembly comprising: a trigger including a manipulation portion,a linkage portion, and a pivot portion disposed between the manipulationand linkage portions, the pivot portion configured for pivotableengagement with a housing of a surgical instrument such that moving themanipulation portion in a first direction relative to the housing pivotsthe pivot portion relative to the housing to thereby move the linkageportion in a second, opposite direction relative to the housing; a firstlinkage defining a first floating end portion and a second pivoting endportion, the second pivoting end portion configured for pivotableengagement with the housing; a second linkage including a crossbar andan upright, the crossbar pivotably coupled to and extending between thelinkage portion of the trigger and the first floating end portion of anarcuated linkage; and a slider block operably engaged with the uprightof the second linkage such that movement of the upright in response tomovement of the manipulation portion of the trigger relative to thehousing translates the slider block along a longitudinal axis relativeto the housing.
 2. The trigger mechanism according to claim 1, whereinthe manipulation portion of the trigger is disposed on one side of thelongitudinal axis and wherein the linkage portion of the trigger ispivotably coupled to the crossbar of the second linkage on a second,opposite side of the longitudinal axis.
 3. The trigger mechanismaccording to claim 1, wherein the linkage portion of the triggertraverses the longitudinal axis.
 4. The trigger mechanism according toclaim 1, wherein the second pivoting end portion of the first linkage isdisposed on one side of the longitudinal axis and wherein the firstfloating end portion of the trigger is pivotably coupled to the crossbarof the second linkage on a second, opposite side of the longitudinalaxis.
 5. The trigger mechanism according to claim 1, wherein the firstlinkage includes a body extending between the first floating end portionand the second pivoting end portion, the body traversing thelongitudinal axis.
 6. The trigger mechanism according to claim 1,wherein the slider block is operably engaged with the upright of aT-linkage via a post-opening engagement such that, in response tolongitudinal and vertical motion of the upright of the second linkage,the slider block is only moved longitudinally.
 7. The trigger mechanismaccording to claim 1, wherein the first linkage is arcuate and defines adistally-facing concave side and a proximally-facing convex side.
 8. Thetrigger mechanism according to claim 7, wherein the concave side of thelinkage defines a volume, and wherein the slider block is disposed inthe volume in at least one position of the manipulation portion of thetrigger relative to the housing.
 9. The trigger mechanism according toclaim 1, wherein at least a portion of at least one of: the trigger, thesecond linkage, or the first linkage defines a bifurcated configurationfor receipt of a drive bar therebetween.
 10. The trigger mechanismaccording to claim 1, wherein at least one of: the trigger, the secondlinkage, or the first linkage is formed as a single, monolithic piece ofmaterial.
 11. A trigger assembly of a surgical instrument, the triggerassembly comprising: a trigger including a manipulation portion, aretention portion, and a pivot portion disposed between the manipulationand retention portions, the pivot portion configured for pivotableengagement with a housing of a surgical instrument such that moving themanipulation portion in a first direction relative to the housing pivotsthe pivot portion relative to the housing to thereby move the retentionportion in a second, opposite direction relative to the housing, theretention portion defining a cavity; and a coupling sphere rotatablycaptured within the cavity of the retention portion, wherein at least aportion of the cavity defines an internal surface complementary to anexternal surface of the coupling sphere such that movement of themanipulation portion of the trigger relative to the housing translatesthe coupling sphere along a longitudinal axis relative to the housing.12. The trigger assembly according to claim 11, wherein the manipulationportion of the trigger is disposed on one side of the longitudinal axisand wherein the retention portion of the trigger extends to a second,opposite side of the longitudinal axis.
 13. The trigger assemblyaccording to claim 11, wherein the trigger is formed as a single,monolithic piece of material.
 14. The trigger assembly according toclaim 11, wherein the coupling sphere is formed from first and secondcomponents engaged with one another via snap-fitting.
 15. The triggerassembly according to claim 11, wherein the coupling sphere isconfigured for positioning about a drive bar.
 16. The trigger assemblyaccording to claim 11, wherein the coupling sphere includes an internalpost extending therethrough.
 17. The trigger assembly according to claim11, wherein the retention portion of the trigger includes first andsecond spaced-apart side walls configured for positioning on opposingsides of the coupling sphere.
 18. The trigger assembly according toclaim 17, wherein the first and second spaced-apart side walls includeproximal and distal ends extending inwardly to retain the couplingsphere longitudinally therebetween.
 19. The trigger assembly accordingto claim 11, wherein the retention portion of the trigger includesproximal and distal fork ends configured for positioning at proximal anddistal ends, respectively, of the coupling sphere.
 20. The triggerassembly according to claim 19, wherein the distal fork end includes aconnector connecting first and second fork legs thereof.